1. The Field of the Invention
The present invention relates generally to high speed comparators. More specifically, the present invention relates to high speed comparators in an optical transceiver environment.
2. The Relevant Technology
Computing and networking technology have transformed our world. As the amount of information communicated over networks has increased, high speed transmission has become ever more critical. Many high speed data transmission networks rely on optical transceivers and similar devices for facilitating transmission and reception of digital data embodied in the form of optical signals over optical fibers. Optical networks are thus found in a wide variety of high speed applications ranging from as modest as a small Local Area Network (LAN) to as grandiose as the backbone of the Internet.
The operations of optical transmission devices in an optical network, such as an optical transceiver, are susceptible to their operating environment and to other operational parameters. Changes in operational parameters such as temperature or bias currents can have an effect on the output performance of the optical transmission device. To help monitor any operational parameter changes, the optical transmission device may be implemented with a comparator circuit.
A comparator circuit is used to make comparisons between actual operational parameter values and desired operational parameter values. For example, a comparator may take a measured operational temperature value and compare that with a desired operational temperature value. The result of the comparison may then be reported to other circuitry in the optical transmission device. If the comparison is outside of an acceptable range, then the optical transmission device may take appropriate action. Thus it can be seen that the speed of the comparator circuit is very important. The faster the comparator can produce a comparison result, the faster the optical transmission device can make any needed adjustments.
Many optical transmission devices require separate comparator hardware for every signal that comparisons are performed on. This often means that additional hardware such as multiple digital to analog converters are also needed. This additional hardware is costly and may slow down the speed of the comparator. In addition, many comparator circuits require real time control by a microprocessor while doing a comparison operation. Therefore, what would be advantageous is a high speed comparator that limits the amount of comparator hardware needed to perform comparisons and that operates without the need for real time control by a microprocessor.